Unlockd says its business crumbled after Google threatened to remove its app from the Google Play store

The developer of Unlockd, a mobile app that sends targeted ads to users when they open their smartphones, has filed for bankruptcy in New York as it hunts for financiers to fund litigation against Google, which the startup blames for its demise.

The Australian-based tech startup has accusedAlphabet Inc.’s Google of flexing its dominance to kill a potential competitor in the mobile advertising market. Unlockd’s U.S. subsidiaries filed for chapter 11 protection Friday in the U.S. Bankruptcy Court in New York. The company also...